1. Field of Invention
The present invention concerns a mycotoxin adsorbent, especially for adsorption of aflatoxins and other mycotoxins (non-aflatoxins) in cereals, grains and animal feeds.
2. Prior Art
The term mycotoxin encompasses a group of toxic substances that are formed by different naturally occurring fungi. About 300 to 400 mycotoxins are now known. Cereals and grains are generally considered the natural environment for these fungi. Whereas some types of fungi develop in the still-maturing grain, other types primarily attack grain supplies being stored when a certain minimum moisture and ambient temperature conditions are present.
All so-called mycotoxins have a health-hazardous effect primarily on agricultural animals fed with infected grain, but secondarily on humans as well via the food chain. For example, aflatoxins are responsible for the so-called X-disease of turkeys, which destroyed about 100,000 animals in Great Britain in 1960/61, which had been fed with moldy peanut flour.
Some of the most important mycotoxins are:
Aflatoxins B1, B2, G1, G2: these are formed by various Aspergillus species. Aflatoxin B1 is carcinogenic even in microgram amounts and causes stomach and liver damage.
Ochratoxin is formed by Aspergillus ochraceus and Penicillium viridicatum and causes kidney damage.
Zearalenone is formed by Fusarium graminearum, which grows on corn, barley and wheat. It is an estrogen-like substance that causes fertility disorders and is suspected to be carcinogenic.
Fumonisine is formed by fungi of the genus Fusarium and has been implicated, among other things, in horse deaths.
T2 toxins and T2-like toxins (tricothecenes) are formed by fungi of the genus Fusarium.
Moreover, there are a number of additional mycotoxins, like deoxynivalenol, diacetoxyscirpenol, patuline, citrinine, byssochlamic acid, ochratoxin, sterigmatocystine, monilifomine, ergot alkaloids, ergochrome, cytochalasane, penicillinic acid, zearalenone, rubratoxins, trichothecenes (cf. Rxc3x6mpps, Chemie-Lexikon, 8th Edition, 1985, page 2888), and others, which occur in concentrations that cause health problems in feeds only in isolated circumstances.
Several different toxins that are recognized as causal agents of health problems in humans and animals can be discovered in different feeds by the utilization of sensitive analysis methods. A number of studies have been able to demonstrate that several toxins can occur simultaneously in feeds. This simultaneous occurrence can significantly influence the toxicity of the mycotoxins. In addition to acute damage to agricultural animals that receive mycotoxin-contaminated feed, health impairment in humans has also been discussed in the literature. Such impairment develops after long-term intake of foods, even weakly contaminated with mycotoxins.
In a recent study of suspected feed samples, aflatoxin, deoxynivalenone or fumonisine were found in more than 70% of the investigated samples (cf. Understanding and Coping with Effects of Mycotoxins in Live Dog Feed and Forage, North Carolina Cooperative Extension Service, North Carolina State University; http:/www.ces.ncsu.edu/drought/dro-29.html).
In many cases, the economic effects relative to reduced productivity of the animals, increased occurrence of disease by immune suppression, damage to vital organs and an adverse effect on reproductivity are even greater than the effects caused by death of the animals by mycotoxin intoxication.
A group of aflatoxins can be adsorbed with high specificity by some absorbents, like zeolite, bentonite, aluminum silicate and others, because of their specific molecular structure (cf. A. J. Ramos, J. Fink-Gremmels, E. Hernandez, Prevention of Toxic Effects of Mycotoxins by Means of Non-nutritive Adsorbent Compounds, J. of Food Protection, Vol. 59(6), 1996, page 631-641). However, this is not true for most other mycotoxins. An attempt has been made to expand the adsorption capacity of mineral adsorbents for non-aflatoxins as well.
A dry particulate animal feed additive is described in WO 91/13555, which contains phyllosilicate particles that are coated with a sequestering agent. An increase in sorption rate can be achieved by this process, but complete ( greater than 90%) elimination of the introduced toxins cannot be achieved.
Good results are also described in the prior art with ion exchange resins or high-quality activated carbon, but such solutions are not practical for cost reasons.
Organophilic clays are used, among other things, in the prior art, to treat liquid wastes with organic contaminants, in order to solidify them and facilitate their disposal (cf. EP-0,560,423).
S. L. Lemke, P. G. Grant and T. D. Phillips describe in Adsorption of Zearalenone by Organophilic Montmorillonite Clay, J. Agric. Food Chem. (1998), pages 3787-3796 an organically modified acid montmorillonite clay, which is capable of adsorbing zearalenone. The best adsorption rates were exhibited by clays that were exchanged with cations containing C16 alkyl groups, namely, hexadecyltrimethylammonium (HDTMA) and cetylpyridinium (CP). Noticeable adsorption rates were only achieved from a coating with a cation exchange capacity (CEC) of more than about 75%.
The use of organically modified clay for adsorption of fumonisine B1 is described in Lemke, S. L., Ottinger, S. E. and Phillips, T. D., Book of Abstracts, 216th ACS National Meeting, Boston, 1998. Quaternary ammonium compounds having a C16 alkyl group are used for organophilization.
The task of the present invention is to prepare an adsorbent based on layered silicates (phyllosilicates) that adsorbs not only aflatoxins, but also other important mycotoxins (non-aflatoxins) with high efficiency and, at the same time, is cost-effective so that it can be used in practice. The adsorbent also exhibits stable adsorption of mycotoxins under physiological conditions, as occur, for example, after absorption with the feeds in the digestive tract of animals.
It was surprisingly found that, by appropriate modification of a layered silicate or part of it, mycotoxin adsorbents can be produced that can effectively adsorb both aflatoxins and non-aflatoxins, like zearalenone, ochratoxin, deoxynivalenone, T2 toxins or fumonisine, which are also cost-effective.